Pencil plunger



F. C. DELI PENCIL PLUNGER Filed July 15, 1935 Int/67% 707 2%; G Deb), 3

Patented Oct. 13, 1936 UNITED STATES PENCIL PLUNGER Frank 0. Deli, Chicago, Ill.,

assignor to Autopoint Company, Chicago, Ill., a corporation of Illinois Application July 15, 1935, Serial No. 31,334

2 Claims.

My invention relates to pencils and particularly to a plunger commonly used in such pencils for advancing the lead.

A machine element of the character described should, in order to be useful, possess certain features, thatis, it should be of small diameterusually only slightly greater in diameter than the leads employed-it should have a widened or non-round portion to engage a guideway and to prevent it from rotation therein, and it should be provided with one or more threads or their equivalent for engagement with a spiral track for effecting the reciprocating movement of the plunger.

In my prior Patent No. 1,682,070, of August 28, 1928, I have disclosed a plunger of the described form in which the metal of the wire composing the plungeris displaced laterally, thereby forming projections that cooperate with the threads formed in a tube, and such construction has operated with a degree of satisfaction in a very great number of pencils.

I have found, however, that a construction such as disclosed herein is much more satisfactory for various reasons, in that it provides for greater extent of engagement by the threads and the threaded tube; it assures the cleaning out of the tube of any particles of lead that may collect therein and it effectively avoids jamming or climbing of the threads over the helical convolutions of the tube.

The plunger shown herein is formed by die action, the die being so constructed that the metal that forms the half-thread projections is displaced or extruded substantially equally radially throughout 180 degrees of the diameter of the wire. This results in the formation of a half-thread of substantially uniform depth throughout its extent and with relatively abrupt shoulders at the terminal points of the thread.

My invention will be more readily understood by reference to the accompanying drawing, in which,

Fig. 1 is a side view of a plunger constructed in accordance with my invention, the view being greatly enlarged;

Fig. 2 is a view taken at right angles to that of Fig. 1; and

Figs. 3 and 4 are sectional views taken on the lines 33 and 44 of Fig. 1.

In the drawing, I have shown the plunger as comprising a length of wire Ill, having a fla tened or non-round portion H at its upper end 5 and somewhat reduced in diameter at its lower end as at I2. This reduced portion is of a size to permit it to enter the discharge opening in the tip, while the remainder of the body is of a somewhat greater diameter for added strength. 10 At an intermediate point near the lower end of the wire, I provide two oppositely disposed halfthreads l3|.4, arranged to correspond to the helix within which the plunger operates. These half-threads are of substantially uniform depth 15 throughout their extent and terminate in abrupt shoulders I5. They are formed by die action whereby the metal is extruded or displaced transversely, the metal in the half-threads originally forming a part of the body of the wire. This construction and method difiers materially from the earlier practice where the material was merely displaced laterally in a line parallel to the transverse axis of the wire; in the present instance the material is displaced laterally and radially through substantially 180 degrees, thereby forming a full half-thread with relatively sharp or abrupt shoulders.

I claim:

1. A pencil plunger consisting of a length of wire having a portion of its body displaced laterally to form a helical projection extending substantially 180 of the circumference of the wire, the extent of projection beyond the perimeter of the wire being substantially uniform from end to end of the displaced portion.

2. A pencil plunger consisting of a length of wire having a portion of its body displaced laterally to form a helical projection extending substantially 180 of the circumference of the wire, the extent of projection beyond the perimeter of the wire being substantially uniform from end to end of the displaced portion, the disposed portion terminating in abrupt shoulders thereby forming sharp edges.

FRANK C. DELI. 

